> seems at least plausible that the Israeli security services did in fact know about Oct 7th but chose not to act

Regardless of the facts in this specific event, you can make much the same argument about many of the major 21st century terror attacks - there were multiple warnings leading up to 9/11, and the FBI and CIA had eyes on several of the perpetrators before the attacks. They didn't "choose not to act" in so much as institutional disfunction prevented the dots from being connected or any preemptive action being taken, but from the outside it looks pretty much the same.